There are numerous situations in which construction dust must be contained as best as possible. For example, renovations in offices with computer equipment, renovations in research labs with electronics, and in hospitals where dust could adversely affect the health of the patients. Dust extraction systems are used in these situations, but often to collect dust that has first escaped and is then caught and extracted.
For example, U.S. Pat. No. 4,549,371 discloses an apparatus for collecting dust for a sander. The sander has a generally planar sanding platen affixed to the main body of the sander by several flexible support columns. The sanding platen is driven by an eccentric mounted on a shaft from the main body of the sander. That same shaft drives a fan in a chamber in the main body that is in flow communication with passages through the main body, through the flexible support columns, through a portion of the sanding platen to holes in the platen that are coincident with holes in the sandpaper. Dust from the workpiece being sanded passes through the holes into the platen, through the support columns to the fan chamber without exposing bearings, supporting the shaft and the eccentric, to the dust. As shown in the drawings, there are a few holes adjacent the periphery of the sandpaper that must be carefully aligned with the counterpart holes in the platen and adjacent layer in order for the dust to be extracted. Grooves in layer and sandpaper sheet, when mounted on the underside of layer, define a passage through which dust can be sucked from the surface of the workpiece, from the peripheral edge region of sandpaper sheet and from the vicinity adjacent the sander. Hence, a significant amount of dust escapes from the device and is then sucked up. As the dust under the central section of the device is not extracted directly, the amount of dust escaping is considerable. Further, the sandpaper must be carefully placed in order to align the holes correctly.
U.S. Pat. Nos. RE40,345, 6,179,696, 6,132,300 and 5,885,146 disclose an oscillating hand tool that has an extractor. A perforated sandpaper sheet may be attached to the outer face of the platen, for example by the use of hook-and-loop fabric such as that sold as VELCRO® glued to face. Holes passing through the platen facilitate the removal of dust etc., from the sanding face through the platen to exhaust outlet via the duct. An extractor hose may be attached to the exhaust outlet. There is no disclosure nor are there drawings providing any further information on the perforations.
Richard® supplies perforated sandpaper for use in sanding drywall. The sandpaper has a thin layer of a material that will attach to the hooks of VELCRO®. The holes are small (1 mm in diameter with about 14 in a row across the sheet of sandpaper (8.5 cm wide and 29.5 cm long) spaced apart by about 4 mm. In use, the perforated sandpaper traps drywall and paint dust in the holes and on the sandpaper, hence it does not allow for ready extraction of the dust. Further, no attempts were made to align the holes with extraction apertures in the sander.
It is preferable that the sandpaper holes are aligned with the holes in the device. This can be difficult to accomplish. US Publication No. 20070232211 addresses this problem by providing a perforated sandpaper alignment device, which is used to accommodate and position perforated sandpapers having multiple through-holes thereon and comprises a seat. The seat has a base; the base has a column, which the perforated sandpapers are put around, and at least one fixing pole, which is arranged corresponding to one through-hole and used to position the perforated sandpapers. Thereby, multiple perforate sandpapers may be put on the seat and positioned by the seat.
Similarly, US Publication No. 20070232210 discloses a fast-perforated sandpaper-replacing device, which is used to attach a perforated sandpaper to a grinder. The device comprises a casing. The casing has a through-hole, an aligner installed on its surface, and a movable member installed thereinside. An elastic element is arranged between the movable member and the bottom of the casing. A perforated sandpaper alignment device, which penetrates the through-hole, is coupled to the movable member. A grinder is aligned to the fast-perforated sandpaper-replacing device with the aligner. When pressed by a force, the grinder further presses down the movable member and the elastic element and moves toward the perforated sandpapers accommodated by the alignment device. Thus, the grinding disc of the grinder can precisely stick onto the topmost perforated sandpaper.
What is needed is a sandpaper sheet that has perforations that are large enough to allow drywall dust, paint dust and the like to travel through the individual apertures freely and that are aligned with the grooves in the platen of a vacuum sander. Preferably, there are numerous apertures, with both the size and number of apertures being selected to allow for good removal of dust while not unduly compromising the sanding surface. Preferably, there will be visual and physical queues to ensure easy and rapid alignment of the apertures with the grooves. More preferably, the apertures will be of sufficient depth to provide a wall contour that further promotes rapid and efficient extraction.